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Head-to-head evidence comparison — which supplement is right for you?
L-Theanine wins 1 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
3 of 4 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
14 of 19 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both L-Theanine and Melatonin have evidence — compare verdict strength side-by-side.
100-200mg
Morning with coffee for focus, Evening for relaxation, As needed for stress
Suntheanine® capsules or powder
0.5-1mg
30-60 minutes before bed
Immediate-release tablet or sublingual
30-60 minutes
30-60 minutes
30-60 minutes
Varies
Same night
1-3 days
Next morning
First week
The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis
Sleep medicine reviews (2025) · Meta analysis · n=897
The findings indicate the potential use of L-theanine in the management of sleep disturbances; however, the lack of studies on "pure" L-theanine warrants further investigation.
Efficiency of Different Supplements in Alleviating Symptoms of ADHD with or Without the Use of Stimulants: A Systematic Review
Nutrients (2025) · Systematic review
The evidence revealed the potential use of supplements as complementary ADHD treatments under clinical guidance.
Analysis of the Effects of Known Sleep-Support Supplements in Relation to Life Habits, Sleep Conditions, and Sleep Problems
Nutrients (2023) · Rct · n=160
All the tested supplements were found to ameliorate sleep problems significantly (Analysis 1).
Melatonin in cancer treatment
The Cochrane database of systematic reviews (2025) · Meta analysis · n=126
We downgraded the certainty of the evidence because of high risk of bias, small sample size, the width of the 95% confidence interval, and indirectness due to inadequate reporting of cancer type.
Comparative Efficacy, Tolerability, and Acceptability of Donanemab, Lecanemab, Aducanumab, Melatonin, and Aerobic Exercise for a Short Time on Cognitive Function in Mild Cognitive Impairment and Mild Alzheimer's Disease: A Systematic Review and Network Meta-Analysis
Journal of Alzheimer's disease : JAD (2024) · Meta analysis · n=4599
Melatonin may be a better potential disease-modifying treatment for cognitive decline in mild AD and MCI.
Melatonin for sleep disorders in people with autism: Systematic review and meta-analysis
Progress in neuro-psychopharmacology & biological psychiatry (2023) · Meta analysis · n=595
According to the global analysis, the wake after sleep onset and night awakening parameters were not statistically significant.
Meta-analysis (n=897) and multiple RCTs support sleep benefits. Studies often used L-theanine in combination with other compounds, limiting pure L-theanine effect attribution. Effects include reduced sleep onset latency and improved subjective sleep quality.
Based on meta-analyses showing 7-12 minute reduction in sleep onset. Higher doses showed diminishing returns and increased morning grogginess. Sublingual forms may be more effective at lower doses.
AI-estimated from published studies. Interpret as directional guidance.
L-Theanine has a higher evidence score (9/10 vs 9/10) and wins in 1 of 3 categories.
For fix sleep schedule / jet lag, Melatonin has a higher relevance score (98 vs 55).
No known interactions between L-Theanine and Melatonin have been documented in our database. However, always consult a healthcare provider before combining supplements.